Field of the Invention
The invention relates to an optical fibre sensor system and a method for determining a location of a disturbance.
Introduction to the Invention
Oil, water, gas and other product pipelines form a critical network in every part of the world and are an easy target for intruders. The pipelines are also susceptible to earthquakes, tsunamis and to other geohazard incidents. Monitoring the pipelines in order to keep the pipelines safe from damage is a major challenge. The long distances, often through remote and hostile territory, make the costs of most conventional monitoring systems prohibitive. If an oil or gas pipeline is damaged it can have devastating impacts on human life and health due to explosions, fire and contamination; environment due to poisoning of flora and fauna, as well as the associated financial losses and damage to both image and reputation.
The pipelines are susceptible to various types of third-party interference, such as deliberate acts (illegal tapping, sabotage) or unintended disruption (construction work, farming). This third-party interference can cause huge financial and environmental damage and loss of reputation to the pipeline operators. A reliable, real-time pipeline monitoring system is therefore required in order to detect events of interest and thereby protect nature, human health and economic interests.
According to a survey in 2009, about 36% of all worldwide pipeline leaks were caused by third party interference (TPI), such as illegal tapping, sabotage or construction work. Examples of the events of interest due to third party interference include: 4 Oct. 2001 Fairbanks Ak. (USA), 990 t oil due to sabotage; 2000 Tschernigow, Ukraine, loss of 500,000 litres diesel due to illegal tapping; 10 Jun. 1999 Bellingham, Whatcorn Creek, Wash. (USA), 880 t petrol due to construction work, financial damage USD 45 million.
Illegal tapping is a major problem in emerging countries like India, China and South America. In 2011 for example, Petroleos Mexicanos (PEMEX) counted 1,324 cases of illegal tapping in Mexico. Every day Pemex estimates a loss of 40,000 litres of oil and gas, which sums up to an annual damage of more than 1 billion US$ of loss. Such damage could be avoided or substantially reduced, if third party interference was detected before or close to the occurrence of the interference.
Many times the pipeline monitoring is done by walking, driving and flying along the pipeline. The annual costs for walking and driving the line vary from €100 to €350 per kilometre. The additional costs for flying the line amount to €4.50 per kilometre. Usually two inspections are performed per month, which adds up to €108 per kilometre (€4.50/km×2 flights/month×12 months). The annual costs are between €208 and €458 per kilometre.